The objective of the proposed research is to identify some of the mechanisms which control the formation of the synaptic contacts in the central nervous system (CNS). In cell cultures of the CNS tissue, the environment surrounding the developing neurons can be easily modified to examine effects of different compounds on synaptogenesis. Surfaces of known composition can be presented to the growing neurons in culture through the addition of sepharose coated beads. Cultures incubated with sepharose beads coated with a variety of compounds (i.e., poly-lysine, Con A., and poly-glutamate), will be examined with phase optics, scanning electron microscopy, and transmission electron microscopy. Preliminary results show that growing neurons in culture form apparent presynaptic elements with coated beads, only when the beads were coated with poly-basic compounds. The beads will take the position of the postsynaptic element. The mechanisms of this neuronal response will be investigated by: (1) modifying the culture medium, (2) using cultures of different neurons, and (3) using different materials for coating the sepharose beads. From the results of these experiments with cultured neurons, experiments can be designed to use coated beads with intact animals.